The Pros and Cons of Low Flow Shower Heads
As more and more Americans are concerned with the environment and saving money, new technologies and regulations are created to address these concerns and strike a balance between individual comfort, energy efficiency, and the environment. I’m sure that many of you have heard about the water restrictions due to the Delta Smelt in California that is seriously impacting farmers, and the threat of drought restrictions in Colorado and the Southeast. Every time there is less rain and increased demand, consumers and politicians try change their behavior in the name of conservation.
The shower constitutes one of the biggest home water usage components, along with lawn sprinklers and toilets. Most days the average American spends about eight minutes in the shower, using approximately 20 gallons of water. That is more efficient than a bath, which typically uses at least 30 gallons; however people use the shower more often.
Some cities are attempting to mandate more efficient shower heads, some suggest employing “Navy Showers” where you would turn off the water while lathering up. Many of these mandated behavior modifications are anathema to most Americans. The hope is for better technologies to maintain the pressure of the shower while saving water and energy.
A 2.5-gallon-per-minute shower head is currently the legal standard. Heads are manufactured with flow restrictor washers, but they do not always save water. It is well known that consumers often remove them in a procedure that takes about a minute with a small screwdriver or even a butter knife. Some manufacturers even note on their packages that the flow restrictors can be pried off. The rationale for this from the manufacturers is that some homes have lower water pressure and removing the restrictor will improve the performance of the head. Would you want the government to inspect your home’s water system and give you a special waiver to purchase a hi-flow shower head? I thought so. Some people also install multiple shower heads, since each one can have the legally required water flow. Two shower heads can create 5 gallons per minute of flow which produces a “car wash” effect that many people find enjoyable.
The alternative is that several manufacturers have been developing low flow shower heads that maintain water pressure through the use of a turbine or a Venturi vacuum. Both are attempts to make the flow feel strong by reducing the water and introducing air into the stream. This mixture makes the spray feel as forceful as an all water stream. To see this for yourself take the aerator of a sink and turn the water on, the flow of the water is higher, but it is all water. With the aerator back on, you can see that the water is lighter due to the air entrained into the water stream, but the feel is about the same. Note: This would be a good time to clean your aerator too!
The benefit is that a turbine shower head will use about 12 gallons of water for an 8 minute shower while a Venturi shower head will use about 8 gallons for the same time.
The downside of both of these heads is that while the water usage is reduced, the air that is mixed into the water stream makes smaller water droplets that cool quicker. This means that the water temperature would need to be increased to maintain a similar shower temperature. So you will be saving water, but increasing the energy demand through water heating, some studies have shown that the energy increase can be as much as 10% greater for low flow shower heads over traditional ones. Another side effect would be for homes that have very hard water, as the minerals will deposit on the surfaces of the shower head more quickly and reduce the head’s effectiveness.
Because low flow heads deliver less water, they're more likely to scald you if there is a sudden decrease in the cold water pressure, such as when a toilet is flushed. Scalding should not occur in bathrooms served by ¾ inch supply lines or where thermostatic mixing valves, anti-scald valves, or pressure-balancing valves have been installed.
If your shower water currently rises in temperature when someone flushes the toilet, you can install an anti-scald valve. You can also lower the temperature on your water heater to 120 degrees F or lower.
The Environmental Protection Agency’s (EPA) WaterSense program stamps a seal of approval on bathroom fixtures that save water but perform well. The labels can be found on some toilets and faucets, and are scheduled to go on shower heads in 2010. The EPA's proposal is to label shower heads that spray less than two gallons per minute which the agency thinks is beneficial and attainable. That would result in an average eight-minute shower that uses some 16 gallons of water, 20% less than with a conventional shower head.
Eventually, there will need to be a happy medium where we can save water, save money, and keep the politicians out of our showers.